Refrigerant leak-detection systems

ABSTRACT

A refrigerant leak-detection system is provided to monitor a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit. The system comprises a sensor positioned in the ventilated environment to measure a level of refrigerant/refrigerant by-products in the ambient air, and a detection controller to receive signals associated with the level of refrigerant/refrigerant by-products in the ambient air and to perform an action as a function of the signals. The detection controller stops a ventilation unit for given periods of time to allow the sensor to measure the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time. A method for monitoring the level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority on U.S. Provisional PatentApplication No. 60/982,572, filed on Oct. 25, 2007.

FIELD OF THE APPLICATION

The present application relates to refrigeration systems, and moreparticularly to leak detection for refrigeration systems.

BACKGROUND ART

The declining condition of the environment is a growing concern. Globalwarming has had severe repercussions on the climate of numerouscountries. One of the factors responsible for global warming isgreenhouse-effect gases.

One source of greenhouse-effect gases is the refrigerant used in thefood industry. Accordingly, refrigerants have evolved to be less harmfulto the environment. However, the refrigerants used today still producegreenhouse-effect gases if exposed to ambient temperatures. It istherefore desirable to produce refrigeration systems that are asleakproof as possible. On the other hand, it is also desirable toprovide safety systems to measure refrigerant leaks to quickly reducethe exposure of refrigerants to ambient conditions.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present application to provide a novelrefrigerant leak-detection system and method.

Therefore, in accordance with the present application, there is provideda refrigerant leak-detection system of the type used to monitor a levelof refrigerant/refrigerant by-products in ambient air in aclosed/semi-closed ventilated environment enclosing a refrigerationunit, comprising: a sensor positioned in the ventilated environment, thesensor being provided to measure a level of refrigerant/refrigerantby-products in the ambient air; and a detection controller for receivingsignals associated with the level of refrigerant/refrigerant by-productsin the ambient air, and for performing an action as a function of thesignals, the detection controller stopping a ventilation unit for givenperiods of time to allow the sensor to measure the level ofrefrigerant/refrigerant by-products in the ambient air during the givenperiods of time.

Further in accordance with the present application, there is provided amethod for monitoring a level of refrigerant/refrigerant by-products inambient air in a closed/semi-closed ventilated environment enclosing arefrigeration unit, comprising: stopping a ventilation unit fromcirculating air in/out of the closed/semi-closed ventilated environmentat given periods of time; measuring the level of refrigerant/refrigerantby-products in the ambient air during the given periods of time; andactuating an alarm if the level of refrigerant/refrigerant by-productsis away from a threshold value.

Still further in accordance with the present application, there isprovided a method for monitoring a level of refrigerant/refrigerantby-products in ambient air in a closed/semi-closed ventilatedenvironment enclosing a refrigeration unit, comprising: temporarilystopping a ventilation unit from circulating air in/out of theclosed/semi-closed ventilated environment at given periods of time;measuring the level of refrigerant/refrigerant by-products in theambient air during the given periods of time; and stopping therefrigeration unit at least partially if the level ofrefrigerant/refrigerant by-products is above a threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a refrigerant leak-detection system inaccordance with a preferred embodiment of the present application; and

FIG. 2 is a flow chart illustrating a method for monitoring a level ofrefrigerant/refrigerant by-products in ambient air in aclosed/semi-closed ventilated environment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a refrigerant leak-detection system inaccordance with a preferred embodiment is generally shown at 10. Thedetection system 10 operates in association with a refrigeration unit ina closed/semi-closed environment, such as a mechanical room.

In the embodiment of FIG. 1, the refrigeration unit A is confined to amechanical room B. The refrigeration unit A is typically a mechanicalapparatus or apparatuses in which a refrigerant circulates. Forinstance, the refrigeration unit A is a refrigeration pack having aplurality of compressors, as well as appropriate valves, piping networkand/or headers, an oil-separation system (for compressors using oil),satellite compressors, amongst other items. As illustrated in FIG. 1,pipes are connected to the refrigeration unit A for the inflow andoutflow of refrigerant to/from the mechanical room B. The mechanicalroom B typically hosts mechanical equipment, such as the refrigerationunit A, as a function of the nature of the building featuring themechanical room B.

Mechanical rooms are often provided with ventilation units. In theembodiment of FIG. 1, a ventilation unit C is provided to exhaustambient air from the mechanical room B. Optionally, the ventilation unitC also lets air into the mechanical room B, for instance to controltemperature in the room B, or to ensure the quality of the air in theroom.

In a preferred embodiment, the detection system 10 has a leak-detectioncontroller 11 connected to a leak sensor 12 and to an alarm 13.

In the preferred embodiment, the leak-detection controller 11 isprovided to control the actuation of the ventilation unit C in view ofreadings taken by the leak sensor 12. The leak-detection controller 11stops actuation of the refrigeration unit A in case of emergency, andactuates the alarm 13.

The leak sensor 12 is provided to measure the level of refrigerant orrefrigerant by-products in the ambient air of the mechanical room B (forinstance in terms of ppm).

The alarm 13 is provided to signal a problem (e.g., refrigerant leak,inoperative leak sensor 12) as detected by the leak sensor 12.

The leak-detection controller 11 is a processing unit (e.g., acomputer). The controller 11 is connected to the leak sensor 12 so as toreceive reading signals therefrom. The reading signals are associatedwith a level of refrigerant or refrigerant by-products (hereinafterrefrigerant) in the ambient air. The controller 11 is programmed withthreshold values for the level of refrigerant in the ambient air, atwhich safety procedures are triggered, such as actuating the alarm 13,stopping the refrigeration unit A, amongst other examples.

The controller 11 is also connected to the ventilation unit C. Morespecifically, the constant air circulation in the mechanical room Bresults in an air change that maintains the level of refrigerantrelatively low in the air. Accordingly, the controller 11 has aninternal clock that is programmed so as to periodically stop theventilation unit C for a given amount of time. The periodic stops of theventilation unit C allow the refrigerant level to increase if there is aleak in the refrigeration unit A. Alternatively, the flow of air of theventilation unit C may be reduced during these periods.

Accordingly, referring to FIG. 1, the detection system 10 has at leastthe leak sensor 12 positioned appropriately in the mechanical room B soas to measure the level of refrigerant in the air. The leak-detectioncontroller 11 does not need to be positioned in the room B. Moreover,through appropriate networks, the leak-detection controller 11 can bepositioned off-site. It is also considered to provide the leak-detectioncontroller 11 with interfaces, such that the levels of refrigerant canbe monitored off-site.

It is considered to operate the leak sensor 12 continuously, and notsimply during the periodic stops of the ventilation unit C. Therefore, aleak resulting in a significant increase in the level of refrigerant inthe ambient air is likely to be detected sooner.

The alarm 13 is preferably positioned outside the mechanical room B. Inan embodiment, the alarm 13 is a visual indicator (e.g., flashinglight), or an audio indicator. In another embodiment, in which theleak-detection controller 11 is connected to a control station, thealarm 13 is a signal of any form on a screen of the control station(e.g., pop-up window, warning email, etc.). The alarm is to prompt theoperator of the refrigeration unit A to service the refrigeration unitA.

The leak-detection controller 11 is optionally connected to an operatingsystem of the refrigeration unit A. Therefore, in the event that thereading signals obtained from the leak sensor 12 indicate high levels ofrefrigerant in the ambient air, the controller 11 may temporarily endoperation of the refrigeration unit A to stop or reduce the increase inthe ambient air of the level of refrigerant.

Now that the components of the refrigerant leak-detection system 10 havebeen described, an embodiment of a method 20 of operation is set forth,with reference to FIG. 2.

According to Step 21, the ventilation unit C is stopped for a givenperiod of time. The leak-detection controller 10 periodically stops theventilation unit C from operating. Accordingly, there is limited flow ofair into/out of the mechanical room B for a given amount of time. Forinstance, in every 60 minutes, 5 minutes are dedicated to the periodicstop of the ventilation unit C.

According to Step 22, when the refrigeration unit A is operating butwhile the ventilation unit C is stopped, the leak sensor 12 measures thelevel of refrigerant or refrigerant by-products in the ambient air.However, the measures may be constant as well.

The leak-detection controller 11 receives the reading signals from theleak sensors 12 and compares the reading signals to threshold values todetermine whether any safety procedure must be initiated. Thismonitoring is performed throughout the operation of the refrigerationunit A, and not only during the periodic stops of the ventilation unitC. According to Decision 23, it is determined whether the level ofrefrigerant or refrigerant by-products in the ambient air is outside agiven threshold.

According to Step 24, if the level of refrigerant or refrigerantby-products in the ambient air is outside a given threshold, an actionis performed by the leak-detection controller 11. Amongst the safetyprocedures, the controller 11 may trigger the alarm 13 to producedifferent types of warning signals as a function of the measured levelof refrigerant in the ambient air. Optionally, the controller 11 maymodify the rate at which measurements are taken by the leak sensor 12,or may increase the number of periodic stops or the duration of thestops. Alternatively, the controller 11 may stop the refrigeration unitA if the measured level of refrigerant in the ambient air is above amaximum threshold.

According to Step 25, if the level of refrigerant or refrigerantby-products in the ambient air is within a given threshold, in anembodiment in which the ventilation unit C is controlled by theleak-detection controller 11, the ventilation unit C is turned back on.Moreover, after Step 24, the ventilation unit C is restarted accordingto Step 24 to exhaust the refrigerant/refrigerant by-products from theclosed environment.

It is pointed out that the leak-detection controller 10 is notnecessarily connected to the ventilation unit C. For instance, it isconsidered to program the ventilation unit C such that it stopsautomatically at predetermined periods. In such a case, theleak-detection controller 10 does not need to be connected to theventilation unit C as it does not need to stop its operation.

1. A refrigerant leak-detection system of the type used to monitor alevel of refrigerant/refrigerant by-products in ambient air in aclosed/semi-closed ventilated environment enclosing a refrigerationunit, comprising: a sensor positioned in the ventilated environment, thesensor being provided to measure a level of refrigerant/refrigerantby-products in the ambient air; and a detection controller for receivingsignals associated with the level of refrigerant/refrigerant by-productsin the ambient air, and for performing an action as a function of thesignals, the detection controller stopping a ventilation unit for givenperiods of time to allow the sensor to measure the level ofrefrigerant/refrigerant by-products in the ambient air during the givenperiods of time.
 2. The refrigerant leak-detection system according toclaim 1, wherein the detection controller is connected to theventilation unit to control a ventilation of the ventilated environment.3. The refrigerant leak-detection system according to claim 2, whereinthe detection controller modifies a time delay between the given periodsof time as a function of the signals received.
 4. The refrigerantleak-detection system according to claim 1, wherein the action performedby the detection controller comprises actuating an alarm.
 5. Therefrigerant leak-detection system according to claim 4, wherein thealarm is a visual alarm on a monitor associated with the detectioncontroller.
 6. The refrigerant leak-detection system according to claim5, wherein the visual alarm is an off-site visual alarm.
 7. Therefrigerant leak-detection system according to claim 1, wherein thedetection controller is connected to the refrigeration unit and theaction performed by the detection controller comprises stopping at leastpartially the refrigeration unit.
 8. The refrigerant leak-detectionsystem according to claim 1, wherein the sensor measures the level ofrefrigerant/refrigerant by-products only during the given periods oftime.
 9. The refrigerant leak-detection system according to claim 1,wherein the refrigeration unit is a refrigeration pack.
 10. A method formonitoring a level of refrigerant/refrigerant by-products in ambient airin a closed/semi-closed ventilated environment enclosing a refrigerationunit, comprising: stopping a ventilation unit from circulating airin/out of the closed/semi-closed ventilated environment at given periodsof time; measuring the level of refrigerant/refrigerant by-products inthe ambient air during the given periods of time; and actuating an alarmif the level of refrigerant/refrigerant by-products is away from athreshold value.
 11. The method according to claim 10, wherein stoppingthe ventilation unit comprises varying the given period of time forstopping the ventilation unit as a function of the measured level ofrefrigerant/refrigerant by-products.
 12. The method according to claim10, wherein measuring the level of refrigerant/refrigerant by-productsin the ambient air comprises measuring the level during the givenperiods of time and outside the given periods of time.
 13. The methodaccording to claim 10, wherein actuating an alarm comprises actuating avisual alarm on a controller monitor for an operator of therefrigeration unit.
 14. A method for monitoring a level ofrefrigerant/refrigerant by-products in ambient air in aclosed/semi-closed ventilated environment enclosing a refrigerationunit, comprising: temporarily stopping a ventilation unit fromcirculating air in/out of the closed/semi-closed ventilated environmentat given periods of time; measuring the level of refrigerant/refrigerantby-products in the ambient air during the given periods of time; andstopping the refrigeration unit at least partially if the level ofrefrigerant/refrigerant by-products is above a threshold value.
 15. Themethod according to claim 14, wherein stopping the ventilation unitcomprises varying the given period of time for stopping the ventilationunit as a function of the measured level of refrigerant/refrigerantby-products.
 16. The method according to claim 14, wherein measuring thelevel of refrigerant/refrigerant by-products in the ambient aircomprises measuring the level during the given periods of time andoutside the given periods of time.